Fast-charging, battery charging systems are distinguished from other battery charging systems in that they operate to produce a battery charging output with a higher kilowatt output and approximately twice, or greater, the charging rate than traditional battery charging systems. An industrial-type, fast charging, battery charging system can include a power supply connected to one or more charging stations, and the charging stations can have output currents up to 500 A or greater, and power outputs up to 30 kW and greater. Compatible battery voltages are typically 12 to 80 volts from a lead-acid battery or battery bank. The industrial-type, fast charging, battery chargers can typically be used for charging lift trucks, fork lifts, golf carts, and the like, which chargers operate at relatively higher electrical power levels to charge a 12-80 volts direct current (VDC) battery system. In these systems, the battery is the main power source for driving the fork lift, golf cart, and the like.
These fast charging systems can have a primary side switched-mode power supply that converts a mains alternating current (AC) electrical power into a suitable direct current (DC) electrical power. A chopping circuit may also be included to convert the DC electrical power to charging power. In general terms, the switched-mode power supply can include input terminals for mains input, and an input rectifier and filter for filtering and rectifying the mains input, an inverter for converting the rectified input power to a higher frequency, a high frequency transformer which converts the voltage up or down to the required output level on its secondary winding(s), and another rectifier and/or output chopper circuit to provide a suitable DC battery charging power. Mains power can be 120, 240, 480, 600, or higher, VAC, and single phase or multiphase being typical for the higher voltages. A switched-mode power supply has the advantage of providing a relatively high frequency to the transformer, which allows the transformer to be smaller for a given current capacity, as transformer size is inversely related to operating frequency.
Fast-charging, battery charger, power supplies can generally require a number of heat generating electrical devices such as transformers, power modules which may have insulated gate bipolar transistor (IGBT) switching modules, inductors, rectifiers, transducers and the like interconnected through busses or bus bars, circuit boards, connectors, cables, etc. Because of the high current and/or voltages involved, such power supplies can have electrical devices as mentioned that generate a considerable amount of heat which needs to be dissipated in order to prevent damage to the battery charging power supply, and to increase the reliability of the battery charging power supply. Some of these devices (e.g., transformers) are relatively robust, whereas other (e.g., the integrated circuits used on the power modules and other circuit boards) are susceptible to contaminants and other elements such as static electricity.
Typically, the initial rectified voltage is provided to a bus (i.e., a conductor or conductors that provides a fixed or varying potential to a variety of components), which is disposed across a capacitor bank for filtering. The inverter (switched circuit) then inverts the electrical power and converts it to a higher frequency. Some designs, such as those including chopper circuits, have a second bus which is further processed by the output circuit.
It is also well know that fast-charging battery charging systems can become hot during use. Components can be cooled by blowing air past them, but it is also known that blowing air can bring particles past sensitive components, such as integrated circuits, switches, etc., which could damage them. Thus, there are competing concerns, cooling components and keeping components safe from dirt, other contaminants, etc.
Higher output fast-charging battery charging systems have a bus or bus bar that can become very hot due to the high currents and corresponding I2R heating. Generally, as the battery charging current output rises, the bus or bus bar must be able to dissipate more heat. Prior art designs do not adequately address the design of bus or bus bars to reduce/dissipate heat so that they do not need to have air blown past them. Bus or bus bar(s), as used herein, can refer to one bus or bar (or bar at one potential), or multiple busses or bars at different potentials, and bus or bar refers to the conductor, not a particular shape.
Accordingly, what is needed in the art is a fast-charging battery charging system power supply that has a bus and/or a bus assembly that can be used at high current without overheating, and which has inherent heat dissipation capabilities.